Seeing very slow performance with svnadmin verify

[Eric Johnson <er...@tibco.com>]

Using: svnadmin --version
svnadmin, version 1.9.4 (r1740329)

The first time I ran into this, I simply added the -M option. Since the 
default is reported just "16", I added "-M 384", and noticed a 
significant speed bump. However, I've got a repository where even this 
big jump didn't fix the performance problems. Current behavior is to 
appear to pause significantly, then report two versions verified. The 
pause lasts on the order of thirty seconds.

Since I have on the order of 230,000 additional commits to check, I'm 
looking at 39 days before my repository finishes verifying. That's not 
really acceptable.

Any suggestions? Am I doing something wrong?

Thanks!

Eric.

Re: Seeing very slow performance with svnadmin verify

[Stefan Sperling <st...@elego.de>]

On Tue, Nov 01, 2016 at 12:14:32AM -0700, Eric Johnson wrote:
> Using: svnadmin --version
> svnadmin, version 1.9.4 (r1740329)
> 
> The first time I ran into this, I simply added the -M option. Since the
> default is reported just "16", I added "-M 384", and noticed a significant
> speed bump. However, I've got a repository where even this big jump didn't
> fix the performance problems. Current behavior is to appear to pause
> significantly, then report two versions verified. The pause lasts on the
> order of thirty seconds.
> 
> Since I have on the order of 230,000 additional commits to check, I'm
> looking at 39 days before my repository finishes verifying. That's not
> really acceptable.

I doubt this extrapolation makes sense, because the effort to verify a
revision depends on the nature of the changes made in the revision.
Perhaps some earlier revisions contain huge imports and are thus expensive
to verify?

> Any suggestions? Am I doing something wrong?

Please provide more information about this repository, in particular
the output of 'svnadmin info', and the number of directory entries,
average file sizes, etc. ('svnfsfs stats' will show these numbers).

There are a lot of variables involved so it's hard to give you good
advice without more detailed information. See here for more context:
http://subversion.apache.org/docs/release-notes/1.9.html#fsfs-improvements

There is now a --metadata-only option for 'svnadmin verify' but it's hard
to tell if this would help your particular case since it's unclear which
repository format you are using.
http://subversion.apache.org/docs/release-notes/1.9.html#svnadmin-verify

Re: Seeing very slow performance with svnadmin verify

[Andreas Mohr <an...@lisas.de>]

On Tue, Nov 01, 2016 at 12:14:32AM -0700, Eric Johnson wrote:
> Since I have on the order of 230,000 additional commits to check, I'm
> looking at 39 days before my repository finishes verifying. That's not
> really acceptable.
> 
> Any suggestions? Am I doing something wrong?

You could try to
run strace and/or ltrace with sufficiently detailed cmdline options,
to try to figure out
which system call exactly is involved in the delay/expensive handling.

A 30s pause might perhaps hint at some network / DNS resolve things.

</not_an_svnadmin_expert_here>

HTH,

Andreas Mohr

-- 
GNU/Linux. It's not the software that's free, it's you.